ARCHITECTURE.md

Architecture

The following steps describe the initialization of the application:

• First an early logger is setup to log any issues with config setup.
• The global config is assembled from environment variables, command line arguments and a possible config file.
• A new logger instance is set up using the created configuration.
• Signal handling for double Ctrl-C invocation is set up to terminate the application
• The DO updater service is spawned on a new thread.
• The main thread blocks on regular termination signals to notify the updater thread when to quit.

The following image presents the overall components interacting in the updater service:

• The DnsIpFetcher fetches the public IP from an external service.
• The DomainRecordUpdater queries and update the domain records using DO API

Docker images

Docker builds are done using the cross-compilers provided by the following images

• https://github.com/emk/rust-musl-builder (for linux/amd64)
• https://github.com/messense/rust-musl-cross (for linux/arm/v7 and linux/arm64")

The application images are built using a multi-stage Dockerfile which are ran in Github Actions jobs using a combination of the docker/build-push-action@v2 action and shell code to create and push a multi-arch manifest list to the docker registries.

The final runtime images are based on alpine:latest.